From: Woody Lin woodylin@google.com
[ Upstream commit 63acd42c0d4942f74710b11c38602fb14dea7320 ]
Commit f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") removed the init_idle() call from idle_thread_get(). This was the sole call-path on hotplug that resets the Shadow Call Stack (scs) Stack Pointer (sp).
Not resetting the scs-sp leads to scs overflow after enough hotplug cycles. Therefore add an explicit scs_task_reset() to the hotplug code to make sure the scs-sp does get reset on hotplug.
Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") Signed-off-by: Woody Lin woodylin@google.com [peterz: Changelog] Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Valentin Schneider valentin.schneider@arm.com Link: https://lore.kernel.org/r/20211012083521.973587-1-woodylin@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 6db20a66e8e6..e4551d1736fa 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6677,6 +6677,7 @@ void idle_task_exit(void) finish_arch_post_lock_switch(); }
+ scs_task_reset(current); /* finish_cpu(), as ran on the BP, will clean up the active_mm state */ }